The purpose of this trial is to evaluate the safety and efficacy of combination therapy of aliskiren/hydrochlorothiazide (HCTZ) 150/25 mg and 300/25 mg compared with HCTZ 25 mg in patients with hypertension who do not show response to HCTZ 25 mg over a 4-week period.

Inclusion Criteria:

• Male or female outpatients 18 years old or older.

• Patients with a diagnosis of hypertension defined as follows:

  • Newly diagnosed patients or patients who have not been treated for hypertension within the 4 weeks prior to Visit 1 must have a msDBP >= mmHg and < 110 mmHg at Visit 1.
  • All patients who have been treated for hypertension within the 4 weeks prior to Visit 1 must have a msDBP >= 85 mmHg and < 110 mmHg at Visit 2.
  • All patients must have a msDBP >= 90 mmHg and < 110 mmHg at Visit 5.

• Patients who are eligible and consent to participate in the study

Exclusion Criteria:

• Severe hypertension (msDBP >= 110 mmHg and/or MSSBP >=180 mmHg).
• Previous or current diagnosis of heart failure.
• History of hypertensive encephalopathy or cerebrovascular accident, transient ischemic cerebral attack, myocardial infarction, coronary bypass surgery, or any percutaneous coronary intervention.
• Other protocol-defined inclusion/exclusion criteria may apply